Generally wrasses are fine with Copper Power. The trick is to s-l-o-w-l-y ramp up the copper to therapeutic levels over several days. Small doses spread out to AM & PM over several days allows you the time to observe for the occasional fish that is copper sensitive "before" it is too late to stop the dosing. Copper is after all a poison and some fish just don't do well. Do you have a Hanna HL Copper Checker to monitor the copper level. Its wonderful. Low stress on you and the fish.